Cycles : add a Volume Geometry Node

This splits the volume related data (properties for rendering and attributes) of the Mesh node
into a new `Volume` node type.

This `Volume` node derives from the `Mesh` class since we generate a mesh for the bounds of the
volume, as such we can safely work on `Volumes` as if they were `Meshes`, e.g. for BVH creation.
However such code should still check for the geometry type of the object to be `MESH` or `VOLUME`
which may be bug prone if this is forgotten.

This is part of T79131.

Reviewed By: brecht

Maniphest Tasks: T79131

Differential Revision: https://developer.blender.org/D8538

1 files changed, 3 insertions, 4 deletions

diff --git a/intern/cycles/render/mesh.h b/intern/cycles/render/mesh.h
index d0cf4d557aa..c8286a01e2c 100644
--- a/intern/cycles/render/mesh.h
+++ b/intern/cycles/render/mesh.h
@@ -52,6 +52,9 @@ struct PackedPatchTable;
 /* Mesh */
 
 class Mesh : public Geometry {
+ protected:
+  Mesh(const NodeType *node_type_, Type geom_type_);
+
  public:
   NODE_DECLARE
 
@@ -133,10 +136,6 @@ class Mesh : public Geometry {
   array<int> triangle_patch; /* must be < 0 for non subd triangles */
   array<float2> vert_patch_uv;
 
-  float volume_clipping;
-  float volume_step_size;
-  bool volume_object_space;
-
   array<SubdFace> subd_faces;
   array<int> subd_face_corners;
   int num_ngons;